The present invention relates generally to a recording device and a recording medium for use in recording program information of plural channels in such a manner that the program information can subsequently be simultaneously reproduced together, and a reproducing device for simultaneously reproducing the plural-channel program information from the recording medium. More particularly, the present invention relates to an improved recording and reproducing technique which can effectively simplify the necessary operations for overwriting new program information on selected section of a recording channel of a recording medium which has become no longer necessary.
The multi-channel recording (multiplex recording), usually employed in applications where the number of parts (the number of types of musical instrument sound or the like) to be recorded is greater than the number of recording channels of a recorder used, has been heretofore performed for example by a repetition of the so-called "ping-pong recording" operation. Ping-pong recording generally comprises the steps of first recording some of plural desired parts separately on individual recording channels, then reproducing the thus recorded parts to be re-recorded together (mixed) onto a single empty channel (this is called "ping-pong recording"), and thence overwriting other or new parts separately onto the individual recording channels that have now become unnecessary due to the ping-pong recording (i.e., newly writing the other parts on top of the previously recorded information on the now-unnecessary recording channels so that the previous information is no longer left on the channels).
However, in order to overwrite the other parts onto any of the now-unnecessary recording channels in the above-noted manner, the prior art multi-track recorders employing a compact cassette or the like, even when the part to be over-written has a very small number of measures, would require a considerable time, corresponding to the full length (from start to end) of a music piece previously recorded on the recording channel. Namely, if the whole of the recording channel to be used for over-writing has no music piece recorded thereon, it is possible to merely fast-forward the tape to access the start point of a necessary section and then record only on that section, as schematically illustrated in FIG. 2. On the other hand, in the case of a recording channel having any music piece recorded thereon, it is necessary to perform recording while erasing every unnecessary section of the music piece (in other words, recording "silence" on the unnecessary section) as seen from FIG. 3, which would eventually require a considerably long time, corresponding to the full length of the previously recorded music piece.
Further, with the conventional DCC (Digital Compact Cassette) recorders, in order to overwrite a new music piece top of part of a previously recorded music piece, it has been customary to, instead of erasing every unnecessary section, record "mute ID" codes on an auxiliary track of the unnecessary section. This approach would also require a long time, corresponding to the full length of the previously recorded music piece.
Furthermore, with the conventional MD (Mini Disk) recorders, a "UTOC" (Users' Table of Contents) is provided to manage recorded information in terms of track numbers (music pieces). Hence, the UTOC can use its editing function to treat every selected section of a desired track (music piece) as if it were actually erased to thereby save the time and labor needed for erasing the unnecessary section or adding mute ID codes to the entire unnecessary section. But, it would present a significant problem that both the right and left channels of the selected section are treated uniformly as erased, with the result that the section thus treated is completely skipped during next reproduction (and hence the edited music piece is reproduced with undesirable loss or break in its time continuity). An example sequence of such a UTOC editing operation will be described as follows with reference to FIG. 5:
(1) Information about a certain music piece is recorded over addresses A to J (it is assumed in this example that information only at addresses C-D and G-H is to be erased); PA1 (2) To achieve the erasure, the music piece recorded over addresses A-J is divided into five music piece sections, and the UTOC is edited in correspondence to the music piece division; PA1 (3) Then, the UTOC is edited so as to treat, as sections to be erased, the second and fourth music piece sections corresponding to addresses C-D and G-H; and PA1 (4) Finally, the UTOC is edited to combine the information at addresses A-B, E-F and I-J again into a single music piece. After such editing of the UTOC, the music piece is reproduced from addresses A-B, to E-F and to I-J with the sections of addresses C-D and G-H skipped.